Constant pressure refrigeration cycle



March 21, 1967 Filed 001;. 21, 1965 J. B. RUSSELL CONSTANT PRESSURE REFRIGERATION CYCLE 2 Sheets-$heet 1 'IIIIIIIA'IIII '1 V I fii'fi J I I 1;; E; m? l FIG. 2

|5 V I8 EVAPORATOR SEPARATOR IO 20 1 A GAS RECEIVER F" 22 CONDENSER 2|\ LIQUID RECEIVER FIG. I

INVENTOR JACOB BRUCE RUSSELL BY CALVIN J. LAICHE March 21, 1967 J. B. RUSSELL gsgfigrgg? CONSTANT PRESSURE REFRIGERATION CYCLE Filed Oct. 21, 1965 2 Sheets-Sheet 2 FIG. 5

INVENTOR JACOB BRUCE RUSSELL CALVIN J. LAICHE United States Patent Ofi ice 3,309,897 Patented Mar. 21, 1967 3,309,897 CONSTANT PRESSURE REFRIGERATHON CYCLE Jacob Bruce Russell, 7713 Haney Drive, New Orieans, La. 70127 Filed Oct. 21, 1965, Ser. No. 499,888 12 Claims. (Cl. 62-512) This invention pertains to an essentialy constant pressure refrigeration cycle. More particularly, this invention pertains to an essentially constant pressure refrigeration system can find diverse application in the frigeration art offering distinct advantages over present day conventional refrigeration systems.

A commonly employed refrigeration cycle today is the vapor-compression refrigeration cycle generally utilizing a positive displacement compressor. In such a system, the refrigerant undergoes the processes ofevaporation, recovery, compression, condensation, and liquefaction. While such a system offers many advantages, such as compactness and simplicity, the need of having to compress the cooling medium introduces many disadvantages. For example, compression of the refrigerant in such a system requires considerable power. Therefore, a refrigeration system having the compactness and simplicity of the typical vapor-compression refrigeration cycle, yet eliminating the disadvantage, interalia of having to greatly compress the refrigerant, would be a Welcomed contribution to the refrigeration art.

An object of this invention is to provide an essentially constant pressure refrigeration cycle.

Another object of this invention is to provide a refrigeration cycle having the salient features of the conventional vapor-compression refrigeration cycle yet dispensing with the need of having to greatly compress the refrigerant.

Yet another object of this invention is to provide a refrigeration system utilizing novel means whereby efficient cooling rates are attained while operating at essentially constant pressure.

A more specific object of this invention is to provide a refrigeration cycle employing novel means in a system whereby considerable power is saved.

These and further objects will come to light as the discussion proceeds, as weil as from the drawings, wherein:

FIGURE 1 in the drawing is a schematic of the refrigeration cycle and system of the instant invention.

FIGURE 2 is a sectional view of the novel separator means utilized in the refrigeration cycle of this invention.

FIGURE 3 is a sectional view of a modification of the gas receiver means illustrated in FIGURE 1.

The above objects are accomplished pursuant to the present invention by the provision of an essentially conromonofiuoromethane, dichloroethylene, trichlorotrifluomethyl chloride, ethyl chloride, and the like.

a refrigerant vapor-dry gas mixture, thereby absorbing heat from a zone to be cooled; separating the refrigerant vapor-dry gas mixture at essentially constant pressure into separate refrigerant and dry gas streams; condensing the vaporous refrigerant stream to liquid refrigerant by removing heat therefrom; passing a portion of the dry gas back into the refrigerant vapor-dry gas mixture before separation thereof; and continually returning the dry gas and liquid refrigerant to the zone undergoing cooling. The refrigerant vapor-dry gas mixture is centrifugally separated without materially increasing the pressure of either the separated refrigerant or the dry gas. The pressure differential across the centrifuge is preferably kept below 30 p.s.i., especially less than p.s.i., and

most particularly no greater than 5 p.s.i. Accordingly, the system pressure differential is thus no greater than this differential and operation is conducted at essentially constant pressure.

The refrigerant can be any material capable of being vaporized by the absorption of heat as long as it has a density sufiiciently greater than that of the dry gas so that it can be readily separated therefrom by centrifugation. A refrigerant having a density of from about two to about six times, especially about four times, the density of the dry gas is preferred. It is to be understood that the dry gas must be compatible with the refrigerant, e.g. it must not be absorbable by the refrigerant.

The refrigerant is preferably selected from the group consisting of saturated hydrocarbons, halogenated hydrocarbons and ammonia. Halogen ated hydrocarbons are especially preferred, particularly refrigerant Freon-l2 (dichlorodifiuoromethane) and most particularly Freon- 22 (monochlorodifiuoromethane. Typical other refrigerants suitable for use in the instant invention are: isobutane, methyl formate, methyl chloride, ethyl chloride, methylene chloride, trichlorornon-ofiuoromethane, dichloromonofluoromethane, dichloroethylene, trichlorotrifluo roethane, monochioropentafiuoroethane, and the like.

The dry gas is preferably selected from the group consisting of: hydrogen; nitrogen; helium; neon; argon; krypton; xenon; saturated hydrocarbons, eug'. propane, butane, hexane, and the like; halogenated hydrocarbons, e.g. methyl chioride, ethyl chloride, and the ilke.

Particularly preferred gasses are nitrogen and helium, especially the former since it is inexpensive and has a molecular weight which makes it especially attractive for use with the preferred refrigerants of the present invention. An especially preferred combination of refrigerant and dry gas is thus, monochlorodifiuoromethane and nitrogen since these materials are readily available and have a density ratio which makes them eminently suitable for use in the instant invention.

Among the advantages and features of the present invention is that a substantial reduction in power requirements is realized since the process being conducted at essentially constant pressure, viz, no greater than 30 p.s.i. differential across the separator, dispenses with the need of a compressor. The overall efiiciency per ton of refrigeration of the present process is greater than present day commonly employed vapor-compression refrigeration systems since considerably less power is expanded in centrifugally separating the refrigerant from the dry g-as pursuant to the present process as compared to the large amount of power expended in compressing the refrigerant in a vapor-compression refrigeration system. Accordingly, the present system does not require high pressure compressor equipment whereby savings are effected during construction and maintenance. For example, in a conventional one ton vapor-compression refrigeration unit utilizing a one horsepower compressor plus Ms horsepower for the condenser and evaporator fans, 'a total of 1.125 horsepower is required. However, in the present system, a total horsepower of only 0.180 is required to perform the same amount of cooling, viz, a reduction in power consumption of 84%. Among other advantages of the present system is its capability of being controlled much more closely by keeping the evaporator temperature constant as opposed to the usual method in a vaporcompression system of cycling the compressor on and off. Moreover, the present system is quieter in operation than a vapor-compression system. Additional advantages will become apparent in the ensuing discussion.

A full understanding and appreciation of the instant invention may be readily visualized from FIGURE 1 in the drawings. Dry gas from the gas receiver is passed through the conduit 11 to the evaporator 12 concurrently with liquid refrigerant from the receiver 13 via conduit 14. The recivers 10 and 13 are storage tanks or vessels which serve as hold-up reservoirs for the respective materials. The dry gas and the refrigerant, after entering the evaporator 12, are allowed to become comingled. This is readily accomplished, for example, by maintaining a liquid level in the bottom of the evaporator 12 and passing the dry gas into the liquid by a suitable manifold immersed in the liquid. The refrigerant evaporates in the evaporator 12 in the presence of the dry gas due to the fact that the partial pressure of the refrigerant is reduced thereby. The evaporator 12 can be a conventional tubular heat exchanger comprising a plurality of tubes or a single hairpin tube, a preferably finned to maximize heat transfer.

The refrigerant vapor-dry gas mixture after absorbing heat from the cooling zone is routed by conduit to the centrifugal separator 16. Lines 14 and 15 are preferably joined in a standard joined tube heat exchanger whereby the cool gas leaving the evaporator 12 is used to sub-cool the warm liquid refrigerant leaving the liquid receiver 13. The low density dry gas is separated from the higher density refrigerant in the separator 16 as explained in greater detail hereinafter. The separated dry gas leaves the separator 16 via conduit 17 and is returned to the gas receiver 10 for recycling. The separator vaporous refrigerant is piped from the separator 16 via conduit 18 to the condenser 19 where it is cooled and reduced to a liquid. Buildup of dry gas carried over into the condenser 19 is prevented therein by the conuit 2t) connecting the condenser head or inlet chamber to the inlet (conduit 15) of the separator 16. The condenser 19 can comprise a conventional tubular exchanger or the like, e.g. an air cooled finned hairpin exchanger as commonly employed in small tonnage vaporcompressed air condition units. Where the evaporator 12 and the condenser 19 are both air cooled units, they can be so cooled by fans run by the same motor as in conventional air conditioner window units. However, it is preferred to empoly completely separate fan means for these components. The liquified refrigerant leaves the condenser 19 by way of conduit 21 to the receiver 13 where it is stored for subsequent reuse. Cycling of dry gas and refrigerant is repeated in the above manner Whereby heat is continually removed by the evaporator 12 from the zone being cooled.

FIGURE 2 illustrates a modification of the gas receiver 10 shown in FIGURE 1. At times, pressure surges may be experienced in the system, for example, in the event should a control valve be utilized in line 11 to control flow of the dry gas into the evaporator 12, the control valve being actuated by a thermostat positioned in the cooling zone as a temperature controlling means. To eliminate these pressure .surges, the gas receiver 10 can be constructed as shown in FIGURE 2. The resilient diaphragm means 39 is provided to dampen pressure surges induced in the system by interrupting flow in the line 11. The diaphragm can be constructed of silicone rubber or other suitable resilient material. The weight 31 is pro vided to maintain a constant differential pressure between the liquid refrigerant entering the condenser via line 21 (leaving through line 22) and the dry gas entering via line 17 (leaving through line 11). The weight 31 is adjustable by virtue of the screw adjusting means comprising the weight 32 which can be positioned by the thread means 33. The thread means 33 extends outside of the receiver 1! whereby it can be rotated upon removal of the cap 34. The centrifuge or separator 15 as shown in detail in FIGURE 3 comprises the rotatably mounted hollow shaft means 41 (sleeve fittings at both ends not shown) on which the bafiles 42, 43, and 44 are mounted. The impeller 45 is provided for directing or channeling the refrigerant vapor-dry gas mixture flowing from within the inlet portion of the shaft 41 through the port 46 into contact with the bafiles. The bafile 43 extends to the interperipheral surface of the casing 47 whereby it, in combination of the bafile 42, provides a channel for directing the incoming refrigerant-dry gas mixture flowing between the impeller 45 and the side of the casing 47 into the labyrinth provided by the baffles 42, 43, and 44. The latter are spaced apart to allow the refrigrant vapordry gas mixture to flow and diflFuse therebetween as hereinafter described. The bafl'le 43 as well as the bafiles 44 are provided with the apertures 48 which are radially positioned about half way to about /3 of their radius (baffles) from the shaft 41. The shaft 41 is provided with a multitude of apertures 49 radially spaced over the peripheral surface of the shaft 41. The apertures 49 are positioned between each of the vanes 42, 43, and 44 so that the spaces or openings between the vanes are in open communication with the interior of the hollow shaft 41. The shaft 41 is provided with the plug means 50 to separate the inlet end of the shaft from its outlet end, the outlet end or portion being the apertured length.

The shaft and bafiile assembly is fitted within the casing 47 which is fixed to the shaft 41 and is rotata-bly mounted and supported in a suitable manner, for ex ample, upon trunnions or the like. Each of the bafiles 44 extend in close proximity to the inner peripheral surface of the casing 47 so as to provide the opening or clearance 51 through which refrigerant separated from the refrigerant vapor-dry gas mixture flows towards the outlet end of the separator. The casing 47, together with the bafiles 42, 43, and 44 all integrally mounted on the shaft 41, thus revolves as an assembly with the coming refrigerant vapor-dry gas mixture being separated thereby as hereinafter disclosed.

The casing 47 is separated or partitioned by the member 52 into compartments 58 and 59 which are in open communication via the port 53. The fluid level actuated float means 54 is provided for controlling refrigerant flow between the two compartments. Orifice means of a predetermined size can be utilized in lieu of the flow assembly illustrated in the drawings. Refrigerant flowing through the port 53 passes to the stationary collector or manifold 55 positioned within compartment 58 through which it passes out of the casing 47. The sealing and bearing means 56 and 57 seals the enclosure 58 from the shaft 41 and the exterior of the casing 47. The complete separator assembly 16, including the driving motor means, can be sealed in a pressure vessel of suitable construction to provide a hermetically sealed unit.

In operation, the refrigerant vapor-dry gas mixture, after picking up heat in the cooling zone, enters the separator 16 via the inlet portion of the hollow shaft 41. The plug 50 directs the fluid flow through the port 46. The mixture then flows at low velocity between the impeller 45 and the casing side and thereafter into the opening between the impellers 42 and 43. The mixture continues to flow toward the shaft 41 and due to the centrifugal force created by the gyration of the baffles (viz. the entire separator) is caused to separate into a dry gas stream which,- being lighter, flows toward and into the interior of the hollow shaft 41 through the apertures 49, whereas, the refrigerant vapors being heavier are caused to flow toward the inner peripheral surface of the casing 47. The mixture, upon reaching the location of the apertures 48, diffuses among the rest of the baffles with the heavier refrigerant vapors flowing toward the casing wall and the dry gas flowing toward the shaft 41. The refrigerant vapors which are centrifugally displaced outwardly flow along the inner peripheral surface of the casing 47 through the openings 51 located at the peripheral edge of the vanes 44. This centrifugal separation occurs along the entire length of the baffles 44. The partition or bulkhead 52 stops the flow of refrigerant out of the compartment 59 until the refrigerant is present in suflicient concentration to raise the float 54 thereby allowing fluid to flow through the opening 53. The collector or manifold 55, which is stationary and isolated from the rotative parts by the seal and bearing means 56 and 57, collects the refrigerant vapors and conveys them out of the separator.

The velocity head developed by the impeller 45 at the inlet of the separator is retained at the outlet end by inducing the fluid into the collector 55 at a radius where the velocity is sufficient to produce the head pressure necessary to overcome flow losses in the system, generally 5 p.s.i. or less. Due to the low density of the dry gas relative to that of the refrigerant, the velocity head of the pure dry gas is negligible compared to the velocity head of the refrigerant vapors at the same velocity. Therefore, the pressure of the gas and vapor coming out of the separator is approximately 5 p.s.i. greater than the pressure head of the mixture at the inlet.

It will be apparent to one skilled in the art that various changes and modifications can be made in the present process as well as the unique apparatus of the present invention witthout parting from its true spirit and scope. For example, liquid lift pump means can be located in the line 14 where the liquid receiver 13 is considerably displaced in elevation with respect to the evaporator 12. Morever, a control valve actuated by thermostat means can be provided in the line 11 for controlling the temperature in the evaporator 12. Additionally, where a dry gas is utilized that is heavier than the refrigerant, then the flow of such materials through the separator 16 will be reversed to that described supra, that is, the refrigerant will be collected within the hollow shaft means 41 and the dry gas collected in the collector 55.

I claim:

1. An essentially constant pressure refrigeration process comprising:

(a) evaporating a refrigerant in the presence of a dry gas to form a refrigerant vapor-dry gas mixture there- 'by absorbing heat from a zone to be cooled,

(b) separating the refrigerant vapor-dry gas mixture at essentially constant pressure into separate vaporous refrigerant and dry gas streams,

( c) condensing the vaporous refrigerant stream to liquid refrigerant by removing heat therefrom,

(d) passing a portion of the dry gas back into the refrigerant vapor-dry gas mixture before separation thereof, and

(e) continually returning the dry gas and liquid refrigerant to the zone undergoing cooling.

2. The process of claim 1 further characterized in that the refrigerant vapor-dry gas mixture is centrifugally separated without materially increasing the pressure of either of the separated streams.

3. The process of claim 1 further characterized in that the pressures of the centrifugally separated vaporous refrigerant and dry gas streams are no more than 30 p.s.i. greater than the pressure of the refrigerant vapor-dry gas mixture and the refrigerant has a density of about 2 to 6 times the density of the dry gas.

4. The process of claim 1 further characterized in that the pressures of the centrifugally separated vaporous refrigerant and dry gas streams are no more than 10 p.s.i. greater than the pressure of the refrigerant vapor-dry gas mixture and the refrigerant has a density of about 4 times the density of the dry gas.

5. The process of claim 1 further characterized in that the refrigerant is selected from the group consisting of saturated hydrocarbons, halogenated hydrocarbons, and ammonia and the dry gas is selected from the group consisting of: hydrogen; nitrogen; oxygen; helium; neon; argon; krypton; xenon; saturated hydrocarbons; and halogenated hydrocarbons.

6. The process of claim 1 further characterized in that the refrigerant is monochlorodifluoromethane and the dry gas is nitrogen.

7. The process of claim 1 further characterized in that the refrigerant is monochlorodifiuoromethane which is evaporated in the presence of nitrogen to form a monochlorodifluoromethane-nitrogen mixture which is thereafter centrifugally separated such that the pressures of the separated monochlorodifluoromethane and the nitrogen are no more than 5 p.s.i. greater than their mixture before separation.

8. A refrigeration system comprising:

(a) evaporator means wherein a refrigerant is evaporated in the presence of a dry gas to form a refrigerant vapor-dry gas mixture thereby absorbing heat from a zone to be cooled,

(b) centrifugal separator means connected to said evaporator means for separating at essentially constant pressure the refrigerant vapor-dry gas mixture into separate vaporous refrigerant and dry gas streams,

(c) condenser means connected to said separator means for receiving and condensing the vaporous refrigerant, said condenser being further defined in that a portion of the vaporous refrigerant is returned to the refrigerant vapor-dry gas mixture entering said centrifugal separator,

(d) liquid receiver means connected to said condenser means for receiving the liquidified refrigerant therefrom, said liquid receiver means being connected to said evaporator means, and

(e) dry gas receiver means connected to said centrifugal means for receiving the dry gas therefrom.

9. The system of claim 8 further characterized in that temperature sensing means is provided for determining the temperature of the evaporator means and that control valve means actuated by said sensing means is provided between said evaporator means and said dry gas receiver means for controlling the flow of dry gas therebetween whereby the temperature of said evaporator is automatically controlled at a predetermined temperature.

10. The system of claim 8 further characterized in that the pressure difi erential across the centrifugal separator means is less than 30 p.s.i.

11. The system of claim 8 further characterized in that the refrigerant is monochlorodifluoromethane and the dry gas is nitrogen.

12. Centrifuge means for separating at essentially constant pressure a refrigerant vapor-dry gas mixture into its separate components comprising:

(a) rotatably mounted cylindrical shaped casing means having an inlet and an outlet along its longitudinal axis, said means further comprising partition means positioned perpendicularly to the longitudinal axis of said casing means in contact with the inner peripheral surface of said casing means and in a spaced apart relationship to the outlet end of said casing means, said partition means dividing said casing means into an inlet chamber and an outlet chamber which are in open communication with each other via an aperture provided in said partition adjacent to the inner peripheral surface of said casing means,

(b) fluid level actuated control means mounted on said partition means in operable relationship with the aperture therein whereby fluid flow from the inlet chamber to the outlet chamber is controlled,

(c) baffle means rigidly positioned within said casing means, said baffle means comprising a series of spaced apart conical shaped baflles having apertures therein, and rotatably hollow shaft means positioned along the longitudinal axis of said casing means on which said baflles are mounted, said shaft having apertures therein radially spaced in open communication with the openings between said baflles whereby a refrigerant vapor-dry gas mixture entering the open spaces between said baffies and diffusing throughout said baffles through the apertures therein is centrifugally separated into separate refrigerant and dry gas streams whereby the dry gas flows into said hollow shaft, said shaft also providing an outlet conduit for the vapors entering therein and an inlet conduit for the mixture entering said casing means,

((1) stationary collector means positioned within the outlet chamber of said casing means for receiving fluid flowing from the inlet chamber as governed by said control means, said collector means further defining an outlet conduit for the fluid, and

(e) sealing means for sealing said casing means to said collector means.

References Cited by the Examiner UNITED STATES PATENTS Platen et a1 6249O X Maiuri et al 62490 Bikkers 62-490 Ullstrand 6'249O Andersson 621 19 Taylor 62-490 X Hellstrom 62490 X Dublitzky 621 14 Lindberg 62114 X Fuderer 62114 LLOYD L. KING, Primary Examiner. 

1. AN ESSENTIALLY CONSTANT PRESSURE REFRIGERATION PROCESS COMPRISING: (A) EVAPORATING A REFRIGERANT IN THE PRESENCE OF A DRY GAS TO FORM A REFRIGERANT VAPOR-DRY GAS MIXTURE THEREBY ABSORBING HEAT FROM A ZONE TO BE COOLED, (B) SEPARATING THE REFRIGERANT VAPOR-DRY GAS MIXTURE AT ESSENTIALLY CONSTANT PRESSURE INTO SEPARATE VAPOROUS REFRIGERANT AND DRY GAS STREAMS, (C) CONDENSING THE VAPOROUS REFRIGERANT STREAM TO LIQUID REFRIGERANT BY REMOVING HEAT THEREFROM, (D) PASSING A PORTION OF THE DRY GAS BACK INTO THE REFRIGERANT VAPOR-DRY GAS MIXTURE BEFORE SEPARATION THEREOF, AND 